1. Field of the Invention
The invention relates to a device for processing feedstock.
2. Description of the Background Art
Conventional devices for processing feedstock belong to the field of mechanical process engineering. This concerns changing a source material in its form, size, and/or composition. For example, during crushing, grinding, or deagglomeration, a source material is taken from an original size to a comparatively smaller form. During mixing, different components in the feedstock are prepared so that a uniform particle distribution in the feedstock is achieved at the end. During coating or drying, heat is introduced selectively into the feedstock with the processing of the feedstock, to enclose individual particles and/or to evaporate the residual moisture in the feedstock.
Depending on the type of feedstock and the type of processing, generic devices are equipped with suitable rotor tools, which because of the intense contact with the feedstock are subject to more or less extensive wear, which starting at a certain degree has a negative impact on the quality of the processed end product. For this reason, in prior-art devices the rotor tools are attached removably in the device, to be able to replace worn rotor tools at regular time intervals. At the same time, in terms of economic operation, operators make the effort to minimize the tool changing times, to keep production loss due to down times of the device within reasonable limits.
DE 35 43 370 A1 discloses a mill, through which air flows, with an approximately cylindrical mill housing along whose inner circumference a stator is disposed. The stator with maintenance of a radial working gap encompasses a coaxially oriented rotor, whose drive shaft crosses the housing axially and is held rotatable within bearings. Hub sections are seated axially one behind the other on the drive shaft; of these a hub section each is assigned to a grinding stage. Each hub section carries a rotor disc, on whose outer circumference lastly the radially oriented impact plates are located, which at a radial distance strike along the stator inner surface.
Via a centric feedstock feed in the bottom area of the housing, the feedstock reaches the air current within the device and passes through the housing in the working gap in a helical path. In this regard, the processing of the feedstock occurs during the interaction of grinding plates and stator. After it leaves the working gap, the feedstock is removed via a tangential feedstock exit in the upper housing area of the machine.
A disadvantage of this device arises from the type of attachment of grinding plates to the rotor discs with the use of screws. The arrangement of several grinding stages axially one behind the other and the plurality of grinding plates per grinding stage result in substantial mounting costs during the wear-related change of the grinding plates.
In this regard, improvement can be achieved by the further development of the type of attachment of tools on the rotor. Thus, the devices disclosed in DE 100 53 946 A1, DE 196 49 338 A1, and DE 10 2004 014 258 A1 have rotors, which have retainers that are uniformly distributed along their circumference and in which the rotor tools are inserted axially. A form fit between the rotor and rotor tools assures that the tools are held in the radial direction. This greatly reduces the effort when rotor tools are changed, because the mounting effort with use of screw connections does not apply. Moreover, a considerable amount of work is associated, furthermore, with the successive changes of the individual rotor tools.
In addition, it is a disadvantage in all of the aforementioned devices that the geometric configuration of the crushing zone is possible only within narrow limits. The reason for this is the type of construction, which always envisions axially running grinding plates or hammers which project over the rotor circumference. A variation in the design of the hammers and the turbulence zones lying behind them is therefore possible only to a limited extent.